dmp: deterministic shared memory multiprocessing
DESCRIPTION
ECE 259 / CPS 221 Advanced Computer Architecture II. DMP: Deterministic Shared Memory Multiprocessing. Joseph Devietti et al. Presenter : Tae Jun Ham 2012. 3. 19. Abstract. Most current shared memory multicore and multiprocessor systems are nondeterministic . - PowerPoint PPT PresentationTRANSCRIPT
DMP: Deterministic Shared Memory Multiprocessing
Joseph Devietti et al.
ECE 259 / CPS 221 Advanced Computer Architecture II
Presenter : Tae Jun Ham2012. 3. 19
Abstract Most current shared memory multicore and
multiprocessor systems are nondeterministic.- Non-determinism makes debugging and testing hard.
Previous approaches were based on replay- But replay is only useful for debugging
Based on deterministic inter-thread communication, this paper suggests several ways to achieve deterministic shared memory multiprocessing
Determinism What is Deterministic Parallel Execution?- Executes multiple threads that communicate via shared memory- Should produce the same output if given the same program input
What causes Non-determinism?- Software sources : concurrent threads, the state of memory
pages, power saving mode, disk and I/O buffer, and some OS system calls.
- Hardware sources : state of caches, predictor tables and bus priority controller, and bus arbiters. In other words, almost all microarchitectural structures.
Non-determinism
Non-determinism
DMP-Serial (Fine-Grained)
DMP-Serial (QBcount)
DMP-Serial (Coarse-Grained)
DMP-ShTab Communication-Free Region: Parallel Communication : Serial
Rules- Without token: Read for shared address
Write for own address
- With token:Can do everything
DMP-ShTab
DMP-ShTab
DMP-TM & DMP-TM-Fwd
DMP-TM & DMP-TM-Fwd
DMP-TM & DMP-TM-Fwd
QB-SyncFollow & QB-Sharing
QB SyncFollow : After unlock, pass the token
QB Sharing : After finishing works on shared data, pass the token
Evaluation - Performance
Serial : Linear slowdown with the increasing number of threadsShTab : 38% TM-Fwd : 21%
Evaluation - Quanta size sensitivity
In general, larger quanta is slower. Serial case is less sensitive to quanta size.
Evaluation - Heuristics on quanta size
Effective for ShTab. SyncFollow benefits for some workloads.
Evaluation - Sw-DMP
Author says : In summary, this data shows that Sw-DMP-ShTab does not unduly limit performance scalability for multithreaded applications.
Discussions Can this system deployed?- Too much performance overhead- Implementation Complexity
Which one do you prefer? DMP vs Deterministic replay
Possible power saving with DVFS?